Process of treating mineral oil still bottoms to recover asphalt and fatty acids



Patented Oct. 24, 1933 PROCESS OF TREATING MINERAL on. sTILL BOTTOMS T0 REoovER ASPHALT AND FATTY ACIDS Harry Franklin Angstadt, Philadelphia,Pa., as-

signor to Sun Oil Company, Philadelphia, Pa., a corporation of New Jersey No Drawing.

Application November 3, 193 Serial No.49a242 i 4 Claims; (01. 196-446) 1 In a patent issued to Gellert Alleman December 11, 1928, No. 1,694,463, there is set forth a process of treating the precipitate produced in the alkali treatment of acid-treated mineral oil lubri cating stock, for the purpose of separating the oil from the soap and resins. The soaps and organic or fatty acids producible by the patented process of treating this alkali precipitate or soda sludge are of great commercial value and are commercially used in the manufacture of cutting oils and have a wide variety of other useful applications. However, in the most advanced process of distilling lubricating oils (see the Pew Patout No. 1,761,153, June 3, 1930), thelubricating oil distillates require no acid and alkali treatment and the so-called soda-sludge is not'produced, thereby eliminating the source from which these valuable soaps have hitherto been produced. In investigations which I have made with the object of locating other sources of these fatty acids, I have found that they are obtainable from the final residue, or still bottoms, resulting from the process of the above named Pew patent and havev worked out practical procedures for their separation.

These still bottoms comprise a black asphaltie mixture which is soluble or colloidally dispersible in water and which cannot be purified by heretoforeknown asphalt-purifying methods to produce a high grade asphalt. Another of my discoveries is that inthe process of recovering fatty acids frointhese still bottoms there is also recovered a high grade commercial insoluble-in-water asphalt;

In the process of the above mentioned Pew patent, a certain amount of caustic soda is mixed with the lubricating oil stock before it enters the lubricating oil stills. After the various distillates are removed, there remain black, asphaltic still bottoms which 1 diiier from ordinary asphaltic still bottoms in that they are truly soluble or colloidally dispersed in water. I have determined that this peculiar property of these still bottoms isdue to the presence of a sodium salt, or sodium salts, of certain organic acids, which salts are not present the original petroleum before its passage through the still, but which are reaction productsincident to the distillation process in the presence of sodium hydroxide. The amount of these sodium salts, which L'shall hereinafter designate as soaps, varies with the different crude oils distilled. I have found this variation to be between 10 and 20 per cent. In addition to the sodium salts of the organic acids above referred to, these still bottoms contain petroleum asphalt and petroleum resins, small amounts of sodium sulphide, sodium carbonate and high boili point hydrocarbons; By separating the soaps of these fatty acids from the water-soluble still bottoms and by eliminating the other water-soluble sodium salts, a much more valuable asphalt is obtained than 'Was'presentin the original mix ture and valuable organic acidsare derived from the separated soaps. 1 i

As a first step in the complete process, the anhydrous stillbottoms are dissolved or colloidally dispersed in hot water. It has been found that whenabout 40 volumes of still bottoms are dis: solved or colloidally dispersed in about volumes of hot water, the best yield of soaps and the best grade of water-insoluble asphalt is obtained. While separations can be obtained with lesser and greater volumes of water than above specified, the 7 yields of soap are not as great and the resulting insoluble asphalt is of a lower quality. After the still bottoms have been dissolved or colloidally dispersed in hot water, the solution or dispersion is transferred to a boiler and heat is applied until a steam pressure of 60 pounds (correspondingto a temperature of about 145 C, or 293 F.) is obtained. Under these conditions, maintained usu ally from 24 to 48 hours, the Water takes up the soap present in the still bottoms, and the asphalt floats on top. While the separation of the soap from the asphalt may be efiected at lower and at higher steam pressures, experience has proven that the maximum separation takes place. in the shortest time at about 60 pounds pressure.

Steam pressure as high as 126 pounds (about 174 0., 345 F.) yields no better results; and with the application of steam pressures of about o pounds (about 131 0., 268. F.) a longer time is required for the separation. c a As the solution or. dispersion is cooled, the soapy water, in consequence of agitation by boiling, re-enters the dispersion stage with the asphalt, and no permanent separation is effected. If, however, after a steam pressure of 60 pounds has been attained, air pressure (100 to 125 pounds) is applied so that, on coolin the solution or dispersion cannot boil, and if such air pressure, with permissive gradual reduction, is maintained until the temperature of the solution or dispersion is below its boiling point at atmospheric pressure, a good separation of soap at the bottom and asphalt at the top is obtained.

After cooling below the boiling point, or to such a temperature as will permit of convenient handling and at which temperature it will not foam excessively, the purified asphalt is separated from the soap-water solution or dispersion preferably by withdrawal of the latter, although, alternatively, the asphalt may be withdrawn from the said solution or dispersion into appropriate vessels. The soap-water solution or dispersion is then acidified with sulphuric, hydrochloric or other water-soluble inorganic or organic acids. Under these conditions the soap reacts with the acid and yields water-insoluble organic acids with float on the water. This material also contains hydrocarbons and resinous materials, is of a light chocolate color, and holds entrained with it about 50 per cent. of water. washed with hot water until the final washings no longer react acid to litmus or methyl orange.

For certain purposes these so-called fatty acids, or the soaps produced therefrom by saponification, are adapted for use without further purification. Certain processes for the purification of these fatty acids have been invented by the patentee Alleman hereinbefore specified and form no part of the present invention.

While the process hereinbefore described is an adaptation of the process set forth in said Patent No. 1,694,463, for the extraction of fatty acid soaps from the soda sludge or alkali precipitate from lubricating oil distillates, it will be understood that a feature which I wish to more particularly emphasize is the discovery that still bottoms which are produced in the practice of the lubricating oil distillation process of the said Pew Patent No. 1,761,153 wherein the lubricating oil stock itself is intimately mixed with sodium hydroxide in the course of preparing the stock for distillation into lubricating oil fractions, or still bottoms produced possibly by other processes involving the addition of sodium hydroxide to the stock to be distilled as distinguished from its addition to the distillates themselves, are sources of these valuable and commercially required organic acid derivatives of petroleum. Another and possibly even more important discovery is that in the process of extracting these valuable acids from these asphaltic still bottoms, there is produced, also, not the by-product mineral oil of the process of Patent No. 1,694,463, but a high grade commercial insoluble-in-water asphalt having characteristics which make it salable for uses for which the still bottoms themselves are not adapted. In other words, the'removal from the still bottoms of the fatty acids, with such impurities as are carried away therewith, not only effects a substantial purification of the asphalt, but produces an asphalt of different characteristics, the chief of which is that it is no longer soluble or colloidally dispersible in water but is completely water-insoluble. In the United States, asphalt having this characteristic is especially in demand. The asphalt is not decomposed with the resultant formation of carb'enes; this resulting in an asphalt which shows a materially higher percentage of material soluble in petroleum spirits as compared to the regular grades of asphalt produced by other processes. The asphalt possesses a higher pene- It is repeatedly tration test for given melting or softening points compared to the ordinary or regularly processed asphalt. It will be understood that the insoluble-in-water asphalt which I have produced may be treated in accordance with any known process, such as blowing with air, for efiecting its still better adaptation for certain commercial uses.

While the established commercial process of producing the asphaltic residuum in accordance with the process of said Pew patent involves the addition of caustic soda to the mineral oil lubricating stock, it is clear that the addition of any other alkali adapted to produce alkali salts of organic acids will produce a residuum which may be treated as herein described to produce a purified insoluble-in-water, asphalt and a solution of fatty acid soaps in water of the character herein described; and in specifying the addition of caustic soda it is not my intention to exclude from the scope of my invention the addition of any equivalent substance adapted to leave, upon distillation, a residuum containing equivalent alkali salts of organic acids.

Having now fully described my invention, what I claim and desire to protect by Letters Patent is:

1. The process of producing valuable products from impure soap-containing asphaltic material remaining as a residue after the distillation of lubricating oils in a lubricating oil distillation process adapted to form soaps, which comprises adding water to the residuum and heating under sufficient pressure to prevent boiling and to separate the asphalt from impurities associated therewith without destroying the sodium soaps contained in said impurities, cooling under sumcient pressure to prevent boiling with resultant re-entry of the separated constituents into the emulsion, solution or dispersion stage, and separately removing the purified asphalt and said impurities, the latter containing soaps adapted to yield water-insoluble organic acids.

, 2. The process of producing a purified insoluble-in-water asphalt and fatty acid soaps-from impure asphaltic still bottoms, soluble or'colloidally dispersible in water, remaining as a residue after the distillation of lubricating oils from lubricating oil stock with which has been mixed caustic soda, which comprises adding water to the still bottoms and heating under suflicient pressure to prevent boiling and to separate the asphalt fromthe soaps associated therewith without destruction of the sodium soaps contained in said impurities, cooling undersufllcient pressure to prevent boiling with resultantreentry of the separated constituents into the emulsion, solution or dispersion stage, and separately removing the separated constituents.

3. The process of producing fatty acid derivatives from asphalt base mineral oil. which comprises adding caustic soda to mineral oil containing lubricating oil fractions to be distilled, distilling from the soda-treated oil lubricating oil fractions leaving an impure residuum comprising asphalt soluble or colloidally dispersible in water and sodium soaps, and rendering the asphalt insoluble in water by removal therefrom of ingredients comprising a solution of said sodium soaps in water by heating and cooling under a pressure adapted to prevent boiling and to separate and maintain separated the water-insoluble asphalt and the water solution of sodium soaps.

4. The process of producing fatty acid derivatives from asphalt base mineral oil which comprises adding caustic soda to mineral oil containsoaps without destroying the latter, cooling under v suflicient pressure to prevent boiling with resultant entry of the separated constituents into the emulsion, solution or dispersion stage, and separately removing the asphalt and the water solu- 7 tion of sodium soaps.

HARRY FRANKLIN ANGSTADT. 

